Many of us don't think much more about our car insurance beyond sorting out the cover and making sure details are up to date.

But there a lot of surprising ways that you could invalidate your car insurance, meaning they won't pay out at all if there's an accident.

And some of the honest mistakes go even further - and could land you in court over the threat of a big fine.

The Mirror spoke to CarParts4Less.co.uk , who have been going through terms and conditions to pick out the 10 things people do that make their cover worthless.

Some of these reasons could invalidate your policy and land you with a huge fine (Image: Getty/Image Source)

1. Registering your parent's (or anyone else's) address

Moved house? Changed city? You need to tell your insurer.

That's because where you live has a huge impact on the price of cover - with crime rates, flood risk and more all changing depending on post code.

That means leaving your car registered at your parent's suburban address, while living in the centre of town, gives the insurance company a legitimate reason to simply reject any claim you make.

Oh, and if you think you won't be caught, remember insurance companies have investigative departments (called special investigations unit, or SUI) whose job it is to check things like this when you make a claim.

2. Not counting your commute - even just driving to the train station

Social car use means just that. Driving to and from friends’ houses, seeing your family, going to the supermarket and so on.

Driving to work, including to and from the train station, means you need a different sort of car insurance.

Even if you just drive to the station or work a few times a month, you still need to upgrade to a "social and commuting" policy.

That's because if you have an accident during the drive to the office or station your insurance might refuse to pay out if your policy is social use only.

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7. Driving with pets

The Highway Code states drivers need to ensure ‘dogs or other animals are suitably restrained so that they cannot distract you while you are driving or injure you, or themselves, if you stop too quickly’.

The law recommends a seat belt harness, pet carrier, dog cage or guard as ways of restraining your pet while driving.

Drivers who don’t restrain dogs and cats while on the move are not just breaking the law, they could also be invalidating their car insurance.

That means if you're in an accident, you could be made to pay for any damage to your car AND any other cars involved, not to mention any medical or other costs resulting - something that could easily add up to a five-figure bill.

8. Letting other people drive your car

But - and it's a huge but - there are big differences between the policy they have on their car and the cover they have on yours.

Firstly, large numbers of policies don't let under-25s do this and also exclude certain people based on their job (ie if they're in the motor trade) completely.

There are other risks too – because those that are covered frequently don't realise how little cover they have.

The fully comprehensive policies that do include the ability to drive someone else's car almost always provide just the legal minimum – ie “third party” cover only.

That means if you hit someone or can't prove it was someone else's fault, they will be able to claim. But you will still be on the hook for any damage to the car you're driving and will get no compensation for any injuries you might suffer.

Oh, and if you lend it to someone who it turns out isn't covered their own policy for some reason, that results in an average fine of £271.30, six points on your licence and has even seen you disqualified from driving as a result.

9. You’ve recently changed jobs or been promoted

Your job title is one of the things insurers look at when they decide how much to charge you.

And even minor changes can mean cheaper or more expensive premiums. It makes sense a lot of the time, for example music teachers are likely to be driving with expensive instruments in their car, while English teachers aren't.

However, that also means if you get a new job, or are promoted and your job title changes, you need to tell your insurer.

And failure to do so many mean any claims made after a job change can be denied.

10. Charging for lifts - or even free lifts and car shares sometimes

Organising lift sharing can save everyone cash - be it on the school run, heading to the football or to work.

But some car insurance policies specifically exclude cover for car sharing, whether you make profit or not.

Even policies that do allow it, could void cover if you make a profit from giving lifts - although some allow petrol money and driving costs.

But as soon as you start making cash, you can get classed as a ‘taxi hire service’, making a policy which does not cover this void.